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JoHN c. BAKER, 0E PHILADELPHIA, PENNSYLVANIA, AssicNoR To HENRY DrssrroN, 0E sAME PLACE.

IMPROVEMENT IN SAW-GRINDING MACHINES.

Specification forming part of Letters Patent No. @3&43, dated October 27, 1868.

To all whom it may concern:

Be it known that I, J. G. BAKER, of Philadelphia, Pennsylvania, have invented an Improvement .in Saw-Grinding Machines; and I do hereby declare the following to be ai'ull, clear, and exact description of the same.

My invention relates to that class of sawgrinding machines in which two stones are used for acting on both sides of a saw-blade simultaneously; and my invention consists of two stones which are so arranged that a line drawn through their centers shall be at an angle with the blade ofthe saw; also, in the combination of the above with certain guides.

The object of my invention is to permit the blade to yield to a limited extent to any slight irregularity of the stone, as described hereafter.

In order to enable others skilled in the art to make and use my invention, I will now proceed to describe its construction and operation, reference being had to the accompanying drawing, which forms a part of this specification, and in which- Figure l is a side view of my-improved sawgrinding machine; Fig. 2, a plan view, partly in section; and Figs. 3 and 4, diagrams illustrating my invention.

A and A are two grindstones, the journals B B of which turn in bearings in suitable frames D D and D D', and the saw-blade to be operated on is introduced between the stones, so as to be ground on both sides simultaneously, asin other machines of this class.

Heretofore, however, it has been the practice to so arrange the two stones that a line drawn through their centers shall be at right angles to the blade of the saw. Hence, the periphery of one stone would bear upon the blade at a point directly opposite that where the periphery ofthe other stone was acting on the opposite side of `the blade. There could, consequently, be no yielding of the blade, which would be acted on injuriously by the slightest irregularity in the peripherie-s ot' the stones, the slightest projection on the periphery of one stone seriously aii'ecting the blade as the latter was backed directly by the other stone.

This will be readily understood by referring to red lines in diagram, Fig. 3, in which m, represents the saw-blade, situated at right angles to a line, n', drawn through the centers ot' the two stones.

Discarding this, the old plan of arranging the stones, I so place them, in respect to each other and to the blade to be operated on, that a line drawn through their centers shall be at an angle with the blade, as seen in Fig. 4, where m again represents the blade, and x .r a line drawn through the centers of the stones.

It will be seen that by this arrangement of the stones in respect to the blade one side ot' the latter is acted on by one stone at a point distant from that where the other stone acts on the opposite side ot' the blade; hence the stones would have a tendency to tilt the blade but for the guide-bars E and E', which serve to maintain the blade in a direct course during the operation of the stones.

It will be evident that, owing to this arrangement of the centers ot' the stones in respect to the blade, the latter can yield to any slight irregularity ot' either stone, and, consequently, that my invention overcomes the above-mentioned diculty heretofore met with in machines of this class. t

In the present instance the upper inclined guide-bar, E, is secured to an open frame attached to the frames D D and D D', in such a manner that a large circular saw can be introduced between the stones.

For the same reason the frames D D are a short distance apart from each other, as are also the frames D D.

There are several appliances which it has not been necessary to illustrate or describesuch, for instance, as the devices for imparting lateral motion to the stones, devices which are common to machines ot this class.

Without contnin g myself to the precise construction or arrangement of frame-work or driving mechanism,

I claim as my invention, and desire to secure by Letters Patentl. A saw-grinding machine in which two stones are so arranged that a line drawn through their centers shall be at an angle with the blade of the saw, as and for the purpose herein set forth.

2. The combination of the above with the guides E and E. 1

In testimony whereof I have signed my name to this specication in the presence of two subscribing witnesses.

JOHN G. BAKER.

Witnesses:

E. H. BAILY, HARRY SMITH. 

